The advantages and applications of metal packaging materials

Aluminum is a resource-rich white light metal, and the world’s aluminum production is second only to steel. Its application in the Packaging industry ranks first in non-ferrous metals. In recent years, aluminum has been used more and more in packaging because of its excellent performance. Its density is small, only 1/3 of steel, lighter weight; excellent processing, easy to stamp into a variety of complex shapes; strong corrosion resistance, no rust; barrier properties, shading, and fragrance protection Excellent, can effectively protect the product; high thermal conductivity, easy to sterilize aluminum cans; silvery white, beautiful color, and high reflectivity to light, easy to print, good printing effect; non-toxic and tasteless, will not be due to aluminum Ion escaping creates an odor in the interior of the food; scrap aluminum containers can be re-melted without environmental pollution. As a packaging material, aluminum is generally made into aluminum plates, aluminum blocks and aluminum foils, and aluminized films. Aluminum plates are usually used as canning materials or lidding materials; aluminum blocks are used to make extruded and thinned stretch-formed cans; aluminum foils are generally used for moisture-proof inner packagings or composites and flexible packaging.

Aluminum plate

Pure aluminum plate containing more than 99.9% aluminum, the thickness is generally between 0.25 ~ 0.3mm. It is soft and has low strength, so it is less used as a packaging material, but it is also useful as a wine container. Alloy aluminum plate is made by adding a small amount of alloy composed of magnesium, manganese and copper to aluminum. Aluminum alloys commonly used in packaging are aluminum-magnesium alloys and aluminum-manganese alloys, also known as rust-proof aluminum alloys. The strength and hardness of the aluminum alloy plate are obviously improved, the corrosion resistance is strong, the polishing is good, and the surface is kept bright for a long time. Alloyed aluminum plates are used to make canned containers. When used in fish and meat cans, they do not exhibit the phenomenon of blackening and vulcanization of the tinned cans. They are more of a packaged beverage and do not cause blisters and changes in taste.

With the improvement of the overall level of the beer and beverage manufacturing industry, the amount of aluminum cans in the world is increasing year by year. The per capita consumption of aluminum cans in the United States exceeds 400 cans. The United States is the largest producer and consumer of aluminum cans in the world. It is mainly used for packaging beverages. In European beverage cans, Tin Cans and aluminum cans each account for about half. At present, China's aluminum cans have a relatively low per capita consumption and have broad space for development.

At present, there are eight countries that can produce aluminum alloy cans in the world: the United States, Brazil, Australia, Japan, South Korea, Germany, France, and Russia. There are also some countries and regions that can produce can lids and pull rings, such as our country. Taiwan Province, Canada, Bahrain, Italy, etc.

With the development of the production of cans by Southwest China Aluminum Strip Co., Ltd. and the hot rolling line of Nanshan Group Aluminium Processing Co., Ltd., which was put into operation in early 2007, the Asian Aluminum Group's aluminum industrial park hot rolling line was put into operation at the end of 2007. Bohai Aluminum Co., Ltd. joint trials in 2008. The cans produced in China will compete in the global can market, and China may become one of the six largest can producers in the world. In 2008, China Southwestern Aluminum Strip Co., Ltd. may have a canning output of 70,000 tons, Nanshan Group and Asia Aluminum Group may produce about 30,000 tons, and the national output may reach 100,000 tons, accounting for 55% of domestic demand.

2. Aluminum foil

The aluminum foil is made of pure aluminum with a purity of 99.5% or more and has a thickness of 0.005-0.2 mm. It is light and lustrous, has strong reflection ability, and can be used as a heat-proof insulating package; good barrier property, gas-impermeable body and water vapor; easy to process, easy to process into various shapes; easy to print, glue, paint, coloring, Embossing, printing, etc.; adaptable to temperature, stable in shape at high or low temperatures; excellent shading, excellent fragrance protection, etc. The biggest drawback of aluminum foil is that it is not resistant to acids and alkalis, it cannot be welded, and its tear strength is low. Aluminum foil packaging has the advantages of high barrier properties, light weight, anti-ultraviolet radiation, long shelf life at room temperature, etc., which makes the application of aluminum foil in various packaging fields increasingly. Aluminum foil packaging has been widely used in food, beverages, dairy products, pharmaceuticals, electronic products and other fields.

The use of aluminum foil is very extensive, and experts have divided it into more than 20 varieties according to their application characteristics. Due to the difference in the level of economic development in different countries, there is also a large gap in the aluminum foil consumption structure. In developed countries in Europe and America, the aluminum foil used for packaging accounts for 70% of the total demand. In the Chinese market, aluminum foil is mainly used as raw materials for industrial manufacturing, and packaging aluminum foil accounts for only 30% of total domestic demand. Although the development of aluminum foil packaging is relatively late, the current market is growing rapidly and the prospects are of concern. At present, China can consume 161,300 tons of aluminum foil each year, and the annual cigarette consumption for cigarette packaging is 35,000 tons.

3. Aluminum film

Metallized film is a new type of composite flexible packaging material, in which the aluminized film is the most widely used one. In addition, gold, silver, copper, etc. can also be plated. Aluminum foil is easy to form pinholes during packaging and use to reduce its barrier properties, so aluminum foil is often used as a composite material with polymer plastics, paper or other metal sheets. A special process is used to apply a very thin layer of aluminum on the surface of the packaging plastic film or paper (single or double sided). Because the aluminum plating layer is relatively brittle and easily damaged, it is generally covered with a protective plastic film such as polyethylene, polyester, nylon and the like. The thickness of the aluminized layer is about 300 angstroms, which is thinner than aluminum foil.

The substrate (i.e., the carrier film) of the aluminized film is a plastic film and paper. The most commonly used plastic films are polyester (PET), nylon (NY), biaxially oriented polypropylene (BOPP), polyethylene (LDPE), and polyvinyl chloride (PVC). The first three kinds of aluminum-plated films have excellent adhesion and luster, and are excellent aluminum alloy composite materials. Aluminized polyethylene film is popular because of its low price and good decor. Aluminized polypropylene film can also be made into easy-to-open seals for easy opening of pharmaceutical packaging.

Using a thermoplastic film as a bonding layer, aluminum foil and paper can be combined to form a multilayer aluminum-plastic composite paper. This composite paper combines the high barrier property of aluminum foil, the flexibility of plastic film, the folding endurance and impact resistance of paper, and becomes a high-performance packaging material without causing pollution to the contents and human body. It is easy to meet the hygienic safety standards for packaging; at the same time, because the resin can be decomposed when heated to a high temperature, the paper and aluminum foil can be separated, thus greatly improving the material recycling and regeneration, reducing material waste and environmental pollution.

Aluminum-plastic composite cans are made of aluminum foil, plastic film and kraft paper (cardboard), and can be made into square, cylindrical, rectangular, conical and other forms of packaging cans. This can is generally divided into outer skin, paperboard, inner liner and inner skin. The composite material also has the characteristics of being non-toxic, odorless, and non-contaminating. It can be reused and recycled.

Aluminum foil is mainly used for blister packaging in pharmaceutical packaging. Blister packs are mainly made of polyvinyl chloride (PVC) sheets and 0.02 mm thick aluminum foil. Blister packaging has become the most important packaging method for western medicine tablets and capsules. China's traditional Chinese medicine tablets, powders, capsules, pills and other packaging are gradually changing from paper bags, simple plastic bags and glass bottles to aluminum-plastic blister packaging. Blister packs have the advantages of moisture resistance, portability, safety and health, etc. With the development of drug slow release technology, the market will be even broader.

Aluminized film is a new type of composite packaging material that is both successful and economical. In the past 10 years, it has been widely used in Europe, the United States, and other countries, and has replaced aluminum foil composite materials in many product packaging (for example, in the packaging of cigarettes, aluminum-plated paper is gradually replacing aluminum foil). Aluminized films are mainly used as vacuum packaging for foods such as fast foods, snacks, meats, and agricultural products, as well as packaging and trademark materials for cigarettes, pharmaceuticals, alcohol, cosmetics, and the like.